An Electron Microscopic Study of Platelet Thrombus Formation in the Rabbit with Particular Regard to 5-Hydroxytryptamine Release

Hr, Baumgartner; Jp, Tranzer; Studer, Amy

doi:10.1055/s-0038-1655068

Cited by 25 publications

(11 citation statements)

References 5 publications

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“…During thrombus formation in vivo (for example, by experimentally induced endothelial lesions of ear veins of rabbits) the 5HT storing organelles almost completely disappear. A minor part of osmiophilic organelles persists outside the platelets (Baumgartner, Tranzer & Studer, 1967). It cannot be decided whether the diminution of the 5HT organelles is a consequence of the general ultramorphological changes occurring during platelet aggregation or whether a more specific mechanism is involved.…”

Section: Platelet Aggregation In Vivomentioning

confidence: 99%

Metabolism, Transfer and Storage of 5‐hydroxytryptamine in Blood Platelets*

Pletscher

1968

British Journal of Pharmacology and Chemotherapy

216

105

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In recent years, evidence has been obtained that aromatic monoamines-for example, catecholamines and 5-hydroxytryptamine (5HT)-might function as neurohumoral transmitters in the central nervous system, and knowledge of their transfer, storage and metabolism is therefore important. Direct investigations of these processes, for example, in isolated synaptosomes of the brain, are, however, problematic since these elements have to be separated from their natural environment and connexions by rather crude methods (for example, density gradient centrifugation of brain homogenates). Blood platelets which contain substantial amounts of 5HT seem to be more appropriate models in spite of the fact that the function of the amine in this situation is not well understood. Thus, the platelets can be studied in relatively physiological conditions in vitro-for example, in plasma or artificial buffer systems-and they also have the capacity to metabolize, transfer and store 5HT.Some recent findings in this laboratory concerning the metabolism, transfer and storage of 5HT in blood platelets are reported here. Platelets of various species including man were isolated according to the usual procedures (Bartholini, Pletscher & Gey, 1961) and in most of the experiments incubated in buffers such as Tyrode using disodium-ethylenediaminetetraacetate to prevent platelet aggregation. Experiments with plasma as an incubation medium did not differ markedly from those with Tyrode. METABOLISM Physiological conditionsIn isolated blood platelets incubated for several hours in physiological media such as plasma or Tyrode buffer, the 5HT content is lowered only slightly (by 1-5%) (Fig. 1) Paasonen & Pletscher, 1959). The small amounts of 5HT which are lost from the platelets hardly appear as such in the incubation medium, but in the form of two major metabolites. They show the typical activation and fluorescent spectra of 5-hydroxyindole derivatives and have RF values characteristic of 5-hydroxyindoleacetic acid (5HIAA) and 5-hydroxytryptophol (5HT'ol) on paper and thin-layer chromatography (Fig. 2). Platelets also metabolize exogenous 5HT (Bartholini, Pletscher * Michael Cross Memorial Lecture 1967. 2 A. PLETSCHER Reserpine p-Chlorometamphetamine 100\ 50 0so 1 0 30 60 120 0 30 60 120 Min~utes Fig. 1. Effect of reserpine (2.5 jig/ml.) and p-chlorometamphetamine-HBr (100 jig/ml.) on the metabolism of 5-hydroxytryptamine (5HT) in rabbit platelets incubated in Tyrode at 370 C. The 5HT and 5-hydroxyindoleacetic acid (5HIAA) are expressed as a percentage of the 5HT content in platelets before incubation with the drugs. ----, 5HT of platelets; ...., 5HT of

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Section: Platelet Aggregation In Vivomentioning

confidence: 99%

Metabolism, Transfer and Storage of 5‐hydroxytryptamine in Blood Platelets*

Pletscher

1968

British Journal of Pharmacology and Chemotherapy

216

105

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“…The endothelial cell plays an important role in physiologic hemostasis (1)(2)(3)(4)(5)(6)(7)(8)(9), blood vessel permeability (10-An abstract of a portion of this work appeared in J. Clin. Invest.…”

Section: Introductionmentioning

confidence: 99%

Culture of Human Endothelial Cells Derived from Umbilical Veins. IDENTIFICATION BY MORPHOLOGIC AND IMMUNOLOGIC CRITERIA

Jaffe¹,

Nachman²,

Becker³

et al. 1973

J. Clin. Invest.

6,458

2,694

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“…The fascia saline extract used in our study was cleaned of fat and thor oughly washed in saline and was electron-microscopically shown to consist predominantly of collagen fibers [8], It would, therefore, appear that our extract was free from tissue factors from injured parenchymal cells and subendothelial material like that found in veins by Baumgartner et al [9], The highly increased capacity of the fascia extracts from the patients to induce platelet aggregation in vitro can thus most probably be ascribed to the structure of the collagen in the extracts. The in vitro aggregation curve ob tained in Born's aggregometer also showed the characteristics of those obtained by the purified commercial collagen preparation in that it showed no second wave.…”

Section: Discussionmentioning

confidence: 68%

“…Different tissue components such as collagen [6,20] and the subendothelial filamentous material in the veins [9], have been shown to induce platelet aggregation. Whole tissue samples were shown to induce platelet aggregation most probably mediated by tissue factors released from injured parenchymal cells [21].…”

Section: Discussionmentioning

confidence: 99%

Hyperactive Connective Tissue in Seven Patients with Recurrent Thrombotic Occlusions

Hedner¹,

Nilsson²,

Bergentz³

et al. 1972

Pathophysiol Haemos Thromb

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A saline extract from the fascia of musculus rectus abdominis with increased capacity to aggregate the platelets in vitro was found in two uraemic patients with recurrent obstructive thrombosis frequently complicating the shunts used for haemodialysis, and in five patients with recurrent spontaneous deep venous thrombosis. None of these patients had any other disorder known to predispose to thrombosis. The increased capacity of the fascia extract to induce platelet aggregation may be due to a hitherto unknown cause of thrombosis, namely a defect in the collagen structure or in the subendothelial substances.

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An Electron Microscopic Study of Platelet Thrombus Formation in the Rabbit with Particular Regard to 5-Hydroxytryptamine Release

Cited by 25 publications

References 5 publications

Metabolism, Transfer and Storage of 5‐hydroxytryptamine in Blood Platelets*

Metabolism, Transfer and Storage of 5‐hydroxytryptamine in Blood Platelets*

Culture of Human Endothelial Cells Derived from Umbilical Veins. IDENTIFICATION BY MORPHOLOGIC AND IMMUNOLOGIC CRITERIA

Hyperactive Connective Tissue in Seven Patients with Recurrent Thrombotic Occlusions

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